i'd like your opinion on using eyedrops to clean copper coins. I discovered this trick by chance trying differents stuff i got at home, and i've stick to it for few years now, it's very efficient and the format is very practical : you put few drops and simply rub it gently in a soft tissue for few seconds, and it will get rid of the dirt but leave the patina (can remove the patina too if you bathe the coins in it for 4 hour then rub more vigorously).

I always thought it was very mild components in eyedrops because you know... you are supposed to pour it in your eyes, the part of human anatomy with the most nerves and the most sensitive ones.

But today i looked at the ingredients and the names are kinda spoopy sounding :
>boric acid
>borax
>sodium chloride
>purified water
For 10ml it's 0.18g of boric acid, 0.12g of borax and trace amounts of sodium. So it's mostly purified water.
What do you think? Could it damage copper coins long term?